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Store slow selector flags in a hashmap.

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This reduces the flag setting overhead on a pessimal testcase from over a
second to ~20ms.
This commit is contained in:
Bobby Holley 2017-04-13 15:42:51 +08:00
parent a32596131a
commit 297dc33a9f
5 changed files with 112 additions and 42 deletions
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9
components/script/layout_wrapper.rs
View file

@ -55,6 +55,7 @@ use servo_atoms::Atom;
use servo_url::ServoUrl;
use std::fmt;
use std::fmt::Debug;
use std::hash::{Hash, Hasher};
use std::marker::PhantomData;
use std::mem::transmute;
use std::sync::Arc;
@ -475,6 +476,14 @@ impl<'le> PartialEq for ServoLayoutElement<'le> {
}
}
impl<'le> Hash for ServoLayoutElement<'le> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.element.hash(state);
}
}
impl<'le> Eq for ServoLayoutElement<'le> {}
impl<'le> ServoLayoutElement<'le> {
fn from_layout_js(el: LayoutJS<Element>) -> ServoLayoutElement<'le> {
ServoLayoutElement {

82
components/style/context.rs
View file

@ -9,10 +9,12 @@ use animation::{Animation, PropertyAnimation};
use app_units::Au;
use bit_vec::BitVec;
use bloom::StyleBloom;
use cache::LRUCache;
use data::ElementData;
use dom::{OpaqueNode, TNode, TElement, SendElement};
use error_reporting::ParseErrorReporter;
use euclid::Size2D;
use fnv::FnvHashMap;
use font_metrics::FontMetricsProvider;
#[cfg(feature = "gecko")] use gecko_bindings::structs;
use matching::StyleSharingCandidateCache;
@ -281,10 +283,8 @@ bitflags! {
/// is used by the style system to queue up work which is not safe to do during
/// the parallel traversal.
pub enum SequentialTask<E: TElement> {
/// Sets selector flags. This is used when we need to set flags on an
/// element that we don't have exclusive access to (i.e. the parent).
SetSelectorFlags(SendElement<E>, ElementSelectorFlags),
/// Entry to avoid an unused type parameter error on servo.
Unused(SendElement<E>),
#[cfg(feature = "gecko")]
/// Marks that we need to update CSS animations, update effect properties of
/// any type of animations after the normal traversal.
@ -297,9 +297,7 @@ impl<E: TElement> SequentialTask<E> {
use self::SequentialTask::*;
debug_assert!(thread_state::get() == thread_state::LAYOUT);
match self {
SetSelectorFlags(el, flags) => {
unsafe { el.set_selector_flags(flags) };
}
Unused(_) => unreachable!(),
#[cfg(feature = "gecko")]
UpdateAnimations(el, pseudo, tasks) => {
unsafe { el.update_animations(pseudo.as_ref(), tasks) };
@ -307,12 +305,6 @@ impl<E: TElement> SequentialTask<E> {
}
}
/// Creates a task to set the selector flags on an element.
pub fn set_selector_flags(el: E, flags: ElementSelectorFlags) -> Self {
use self::SequentialTask::*;
SetSelectorFlags(unsafe { SendElement::new(el) }, flags)
}
#[cfg(feature = "gecko")]
/// Creates a task to update various animation state on a given (pseudo-)element.
pub fn update_animations(el: E, pseudo: Option<PseudoElement>,
@ -322,6 +314,59 @@ impl<E: TElement> SequentialTask<E> {
}
}
/// Map from Elements to ElementSelectorFlags. Used to defer applying selector
/// flags until after the traversal.
pub struct SelectorFlagsMap<E: TElement> {
/// The hashmap storing the flags to apply.
map: FnvHashMap<SendElement<E>, ElementSelectorFlags>,
/// An LRU cache to avoid hashmap lookups, which can be slow if the map
/// gets big.
cache: LRUCache<(SendElement<E>, ElementSelectorFlags)>,
}
#[cfg(debug_assertions)]
impl<E: TElement> Drop for SelectorFlagsMap<E> {
fn drop(&mut self) {
debug_assert!(self.map.is_empty());
}
}
impl<E: TElement> SelectorFlagsMap<E> {
/// Creates a new empty SelectorFlagsMap.
pub fn new() -> Self {
SelectorFlagsMap {
map: FnvHashMap::default(),
cache: LRUCache::new(4),
}
}
/// Inserts some flags into the map for a given element.
pub fn insert_flags(&mut self, element: E, flags: ElementSelectorFlags) {
let el = unsafe { SendElement::new(element) };
// Check the cache. If the flags have already been noted, we're done.
if self.cache.iter().find(|x| x.0 == el)
.map_or(ElementSelectorFlags::empty(), |x| x.1)
.contains(flags) {
return;
}
let f = self.map.entry(el).or_insert(ElementSelectorFlags::empty());
*f |= flags;
// Insert into the cache. We don't worry about duplicate entries,
// which lets us avoid reshuffling.
self.cache.insert((unsafe { SendElement::new(element) }, *f))
}
/// Applies the flags. Must be called on the main thread.
pub fn apply_flags(&mut self) {
debug_assert!(thread_state::get() == thread_state::LAYOUT);
for (el, flags) in self.map.drain() {
unsafe { el.set_selector_flags(flags); }
}
}
}
/// A thread-local style context.
///
/// This context contains data that needs to be used during restyling, but is
@ -339,6 +384,11 @@ pub struct ThreadLocalStyleContext<E: TElement> {
/// the rest of the styling is complete. This is useful for infrequently-needed
/// non-threadsafe operations.
pub tasks: Vec<SequentialTask<E>>,
/// ElementSelectorFlags that need to be applied after the traversal is
/// complete. This map is used in cases where the matching algorithm needs
/// to set flags on elements it doesn't have exclusive access to (i.e. other
/// than the current element).
pub selector_flags: SelectorFlagsMap<E>,
/// Statistics about the traversal.
pub statistics: TraversalStatistics,
/// Information related to the current element, non-None during processing.
@ -356,6 +406,7 @@ impl<E: TElement> ThreadLocalStyleContext<E> {
bloom_filter: StyleBloom::new(),
new_animations_sender: shared.local_context_creation_data.lock().unwrap().new_animations_sender.clone(),
tasks: Vec::new(),
selector_flags: SelectorFlagsMap::new(),
statistics: TraversalStatistics::default(),
current_element_info: None,
font_metrics_provider: E::FontMetricsProvider::create_from(shared),
@ -393,9 +444,12 @@ impl<E: TElement> ThreadLocalStyleContext<E> {
impl<E: TElement> Drop for ThreadLocalStyleContext<E> {
fn drop(&mut self) {
debug_assert!(self.current_element_info.is_none());
debug_assert!(thread_state::get() == thread_state::LAYOUT);
// Apply any slow selector flags that need to be set on parents.
self.selector_flags.apply_flags();
// Execute any enqueued sequential tasks.
debug_assert!(thread_state::get() == thread_state::LAYOUT);
for task in self.tasks.drain(..) {
task.execute();
}

6
components/style/dom.rs
View file

@ -20,6 +20,7 @@ use shared_lock::Locked;
use sink::Push;
use std::fmt;
use std::fmt::Debug;
use std::hash::Hash;
use std::ops::Deref;
use std::sync::Arc;
use stylist::ApplicableDeclarationBlock;
@ -275,7 +276,8 @@ pub struct AnimationRules(pub Option<Arc<Locked<PropertyDeclarationBlock>>>,
pub Option<Arc<Locked<PropertyDeclarationBlock>>>);
/// The element trait, the main abstraction the style crate acts over.
pub trait TElement : PartialEq + Debug + Sized + Copy + Clone + ElementExt + PresentationalHintsSynthetizer {
pub trait TElement : Eq + PartialEq + Debug + Hash + Sized + Copy + Clone +
ElementExt + PresentationalHintsSynthetizer {
/// The concrete node type.
type ConcreteNode: TNode<ConcreteElement = Self>;
@ -518,7 +520,7 @@ impl<N: TNode> Deref for SendNode<N> {
/// Same reason as for the existence of SendNode, SendElement does the proper
/// things for a given `TElement`.
#[derive(Debug, PartialEq)]
#[derive(Debug, Eq, Hash, PartialEq)]
pub struct SendElement<E: TElement>(E);
unsafe impl<E: TElement> Send for SendElement<E> {}
impl<E: TElement> SendElement<E> {

9
components/style/gecko/wrapper.rs
View file

@ -67,6 +67,7 @@ use shared_lock::Locked;
use sink::Push;
use std::cell::RefCell;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::ptr;
use std::sync::Arc;
use string_cache::{Atom, Namespace, WeakAtom, WeakNamespace};
@ -705,6 +706,14 @@ impl<'le> PartialEq for GeckoElement<'le> {
}
}
impl<'le> Eq for GeckoElement<'le> {}
impl<'le> Hash for GeckoElement<'le> {
fn hash<H: Hasher>(&self, state: &mut H) {
(self.0 as *const _).hash(state);
}
}
impl<'le> PresentationalHintsSynthetizer for GeckoElement<'le> {
fn synthesize_presentational_hints_for_legacy_attributes<V>(&self, hints: &mut V)
where V: Push<ApplicableDeclarationBlock>,

44
components/style/matching.rs
View file

@ -13,7 +13,7 @@ use atomic_refcell::AtomicRefMut;
use bit_vec::BitVec;
use cache::{LRUCache, LRUCacheMutIterator};
use cascade_info::CascadeInfo;
use context::{CurrentElementInfo, SequentialTask, SharedStyleContext, StyleContext};
use context::{CurrentElementInfo, SelectorFlagsMap, SharedStyleContext, StyleContext};
use data::{ComputedStyle, ElementData, ElementStyles, RestyleData};
use dom::{AnimationRules, SendElement, TElement, TNode};
use font_metrics::FontMetricsProvider;
@ -108,7 +108,7 @@ fn element_matches_candidate<E: TElement>(element: &E,
shared: &SharedStyleContext,
bloom: &BloomFilter,
info: &mut CurrentElementInfo,
tasks: &mut Vec<SequentialTask<E>>)
selector_flags_map: &mut SelectorFlagsMap<E>)
-> Result<ComputedStyle, CacheMiss> {
macro_rules! miss {
($miss: ident) => {
@ -157,7 +157,7 @@ fn element_matches_candidate<E: TElement>(element: &E,
}
if !revalidate(element, candidate, candidate_element,
shared, bloom, info, tasks) {
shared, bloom, info, selector_flags_map) {
miss!(Revalidation)
}
@ -205,7 +205,7 @@ fn revalidate<E: TElement>(element: &E,
shared: &SharedStyleContext,
bloom: &BloomFilter,
info: &mut CurrentElementInfo,
tasks: &mut Vec<SequentialTask<E>>)
selector_flags_map: &mut SelectorFlagsMap<E>)
-> bool {
// NB: We could avoid matching ancestor selectors entirely (rather than
// just depending on the bloom filter), at the expense of some complexity.
@ -235,7 +235,7 @@ fn revalidate<E: TElement>(element: &E,
// child span is subsequently removed from the DOM, missing selector
// flags would cause us to miss the restyle on the second span.
let mut set_selector_flags = |el: &E, flags: ElementSelectorFlags| {
element.apply_selector_flags(tasks, el, flags);
element.apply_selector_flags(selector_flags_map, el, flags);
};
info.revalidation_match_results =
Some(stylist.match_revalidation_selectors(element, bloom,
@ -560,7 +560,7 @@ trait PrivateMatchMethods: TElement {
tasks.insert(EFFECT_PROPERTIES);
}
if !tasks.is_empty() {
let task = SequentialTask::update_animations(self.as_node().as_element().unwrap(),
let task = ::context::SequentialTask::update_animations(*self,
pseudo.cloned(),
tasks);
context.thread_local.tasks.push(task);
@ -698,11 +698,11 @@ trait PrivateMatchMethods: TElement {
shared: &SharedStyleContext,
bloom: &BloomFilter,
info: &mut CurrentElementInfo,
tasks: &mut Vec<SequentialTask<Self>>)
selector_flags_map: &mut SelectorFlagsMap<Self>)
-> Result<ComputedStyle, CacheMiss> {
let candidate_element = *candidate.element;
element_matches_candidate(self, candidate, &candidate_element,
shared, bloom, info, tasks)
shared, bloom, info, selector_flags_map)
}
}
@ -802,9 +802,9 @@ pub trait MatchMethods : TElement {
let mut rule_nodes_changed = false;
let bloom = context.thread_local.bloom_filter.filter();
let tasks = &mut context.thread_local.tasks;
let map = &mut context.thread_local.selector_flags;
let mut set_selector_flags = |element: &Self, flags: ElementSelectorFlags| {
self.apply_selector_flags(tasks, element, flags);
self.apply_selector_flags(map, element, flags);
};
// Compute the primary rule node.
@ -844,9 +844,9 @@ pub trait MatchMethods : TElement {
Vec::<ApplicableDeclarationBlock>::with_capacity(16);
let mut rule_nodes_changed = false;
let tasks = &mut context.thread_local.tasks;
let map = &mut context.thread_local.selector_flags;
let mut set_selector_flags = |element: &Self, flags: ElementSelectorFlags| {
self.apply_selector_flags(tasks, element, flags);
self.apply_selector_flags(map, element, flags);
};
// Borrow the stuff we need here so the borrow checker doesn't get mad
@ -923,10 +923,10 @@ pub trait MatchMethods : TElement {
///
/// Anyway, let's do the obvious thing for now.
fn apply_selector_flags(&self,
tasks: &mut Vec<SequentialTask<Self>>,
map: &mut SelectorFlagsMap<Self>,
element: &Self,
flags: ElementSelectorFlags) {
// Apply the selector flags.
// Handle flags that apply to the element.
let self_flags = flags.for_self();
if !self_flags.is_empty() {
if element == self {
@ -942,21 +942,17 @@ pub trait MatchMethods : TElement {
// Instead, we can read them, and post them if necessary as a
// sequential task in order for them to be processed later.
if !element.has_selector_flags(self_flags) {
let task =
SequentialTask::set_selector_flags(element.clone(),
self_flags);
tasks.push(task);
map.insert_flags(*element, self_flags);
}
}
}
// Handle flags that apply to the parent.
let parent_flags = flags.for_parent();
if !parent_flags.is_empty() {
if let Some(p) = element.parent_element() {
// Avoid the overhead of the SequentialTask if the flags are
// already set.
if !p.has_selector_flags(parent_flags) {
let task = SequentialTask::set_selector_flags(p, parent_flags);
tasks.push(task);
map.insert_flags(p, parent_flags);
}
}
}
@ -1055,7 +1051,7 @@ pub trait MatchMethods : TElement {
let current_element_info =
&mut context.thread_local.current_element_info.as_mut().unwrap();
let bloom = context.thread_local.bloom_filter.filter();
let tasks = &mut context.thread_local.tasks;
let selector_flags_map = &mut context.thread_local.selector_flags;
let mut should_clear_cache = false;
for (i, candidate) in cache.iter_mut().enumerate() {
let sharing_result =
@ -1063,7 +1059,7 @@ pub trait MatchMethods : TElement {
&context.shared,
bloom,
current_element_info,
tasks);
selector_flags_map);
match sharing_result {
Ok(shared_style) => {
// Yay, cache hit. Share the style.